Regenerative heat exchanger



2 1941- ,e. K. w. BOESTAD REGENERATIVE HEAT EXQHANGER Filed Jan. 22, 1937 .2 Shets-Sheet 1 lll v W 1420 fi A {AJATIORNEL 1- a. K. w. BOESTAD 2,

REGENERATIVE HEAT EXCHANGER Filed Jan. 22, 1937 2 Sheets-Sheet. 2,

ga k

Patented Jan. 28,1941

stares PATENT orrica REGENERATIVE HEAT EXCHANGEB,

bin, Stockholm Sweden 1 Sweden,

a corporation of Application January 22, 1937, Serial No. 121,890 In Germany January 23, 1936 4 Claims.

The present invention relates to regenerative heat exchangers, and has particular reference to regenerative heat exchangers of the kind in which a body of heat exchange material which is preferably of multiple plate form is arranged to rotate in a stationary casing having head plates at each end to which the conduits are connected for flow of the media, such as air and combustion gases, between which heatis to be exchanged.

In heat exchangers of the above kind, packings are provided between the rotary portion of the apparatus and the casing and also between the two compartments of the apparatus through which the difierent media flow, the object of these packings being to prevent short circuiting of either of the media from the inlet to the outlet side of the apparatus without passing through the body of heat exchanging material, and also to prevent as far as possible a direct connection between the difierent passages in which the two media/are intended to flow.

Effective sealing of the character desired has. however, proved to be difllcult in apparatus of this kind, particularly in large units, because of the relative movement of parts due to expansion and contraction under the influence of the different degrees of heat to which different parts of the apparatus are subjected.

The difflculty of obtaining satisfactory sealing has been such that heretofore leakage losses of the order of four percent have had to be taken into consideration in even the most favorable cases.

Thepresent invention has for its principal object the improvement of heat exchange structure of the kind under consideration in a manner enabling leakage losses of the kind described to be materially reduced. More particularly, the invention has for its objects improvement of head plate construction and the improvement of certain portions of the rotor construction which cooperate with the head plate structure to provide the seals between the compartments of the apparatus, as will hereinafter more fully appear in conjunction with the following description of a preferred form of apparatus embodying the invention.

Inthe drawings forming a part of this specification and illustrative of this apparatus;

Fig. 1 is a side elevation, partly in section, of heat exchange apparatus embodying the invention; 7

Fig. 2 is a plan View on a reduced scale taken on the line 2-2 of Fig. 1; l

Fig. 3 is an enlarged detail of part of the struc ture shown in Fig. 1;

Fig. 4 is a fragmentary side view on an enlarged scale of sealing structure embodied in the ap aratus shown in Fig. 1; 5 4 g. 5 is a section taken on the line 5--5 of Fig.-

Fig. 6 is a view similar to Fig. 4 but showing the parts in a different relationship; and

Fig, 7 is a section taken on the line 'l-l of 10 Fig. 6.

Referring now more particularly to Figs. 1 to 3, the heat exchanger illustrated is of a well known type and comprises a rotor indicated generally at 2 which is divided by means of cylindrical partil5 tions 4 and radial partitions 6 into a number of segment-shaped compartments filled with heat exchanging material 8 which is advantageously in the form of corrugated plates providing between them a relatively large number-of longi 2Q tudinally extending passages of small cross-sectional area.

On the hotter end of the heat exchange structure the space in the rotor for flow of the fluid media-is advantageously further divided by means of additional cylindrical partitions I0.

The rotor 2 is provided with a central vertical shaft l2 mounted in bearings it and It at the upper and lower ends of the structure respectively, which shaft is driven through the medium of suitable bevel gearing indicated at I8. The weight of the rotor is supported by the beams 20 and 22 to which the weight is transmitted through bearing Id.

Around the rotor 2 and radially spaced therefrom is the cylindrical stationary outer casing 24, this casing being heat insulated from the rotor by means of the circumferential belt of insulating material 26 carried by the rotor. This insulation operates to relieve the stationary casing as far as possible from expansion strains. At its upper and lower ends the casing 24 is provided with annular flanges 28 and 30 respectively.

The stationary head plates 32 and 34 are connected to the conduits for the flow of the media If, for example, the exchanger is used as a preheater for combustion air, the hot combustion gases flow through the side of the heat exchanger at the left of Fig. l in the direction of the arrows 48 and 50, flowing out through the opening 44 in the plates 32' and 36 after having flowed into the exchanger through a like opening in the'bottom plates 34 and 38. The air to be heated flows through the right side of the preheater as viewed in Fig. 1, preferably in counter-current direction as indicated by the arrows 52 and 54, passing through the opening 46 in the upper head plate structure and through a like opening in the bottom head plate structure.

Since the head plates 32 and 34 are contacted by the hot combustion gases, they are subjected to longitudinal expansion and contraction be-' the plate is held against the upper surface of the flange 28 in light contact therewith through the medium of a series of bolts 58 passing through these apertures and suitable bolt holes in the flange 28 such bolts having associated therewith springs 60 located between the retainers 62 and 64. The proper tension on the springs is secured by suitable adjustment of the nuts 66.

As will be evident from Fig. 1, the lower head.

plate 34 is similarly secured to the lower flange ring 30 by means of bolts 68 and springs I0.

As indicated-in ig. 1, circumferential packing members 12 and I4 are arranged at the upperandlower ends respectively of the rotor to prevent fiow of the gaseous media through the space between the outer wall of the rotor and the casing wall 24.

The radially extending packing members at the upper and lower ends of the radial partitions contact respectively the diametral webs of the upper and lower head plate structures as the rotor revolves (the diametral web of the upper head plate structure being shown at 80 in Fig. 2). When these packing members pass in contact with the webs they serve to separate the passage for flow of one heat exchange medium on one side of the apparatus from the passage for flow of the other heat exchange medium on the other side of the apparatus.

In Figs. 4 to '7 there is shown in detail the improved construction according to thepresent invention for insuring proper sealing contact between these packing members and the head plate structure. In these views, which illustrate the bottom packing members 18, the thin packing strips of sheet metal or the like are indicated at 82. These packing strips instead of being secured directly to the partitions 6, as is usually the case, are carried by radially extending plates 84 which at their inner ends are rigidly secured to the hub portion 86 of the rotor 2.

The partitions 6 are provided with a series of vertical slots 88 having open ends and bolts 90 pass through these slots and through suitable bolt holes 92 in the strips 8d. Springs 94 are located under the-heads of bolts 90 so that the bolts, through the action of these springs, serve to resiliently hold the strips 84 against the partition plates 6.

From a consideration of Fig. 1 it will be evident that the lower portion of the rotor structure is subjected to greater expansion than the upperportion. This is due to the fact that the combustion gases enter the, lower portion at higher temperature than they leave the upper portion and the air leaves the lower portion at a higher temperature than it enters the upper portion. Due to this difference in temperature and to the consequent uneven expansion, the rotor structure may in effect be warped by expansion from a condition such as shown in Fig. 4 where the rotor is assumed to be in cold state to a condition such as shown in Fig. 6 where the rotor is assumed to be in a hot state.

If the radial packing members were rigidly attached to the radial partitions, it is evident that at their outer ends they would be pulled away from proper contact with the head plate structures, but because of the rigid attachment of these packing members to the hub portion of the rotor, and the resiliently held slotted connection between the packing members and the partitions, the packing members may and do retain their original and proper position, which provides an efiective seal between the radial partitions and the head plate structures.

Obviously the details of construction may be altered without departing from the spirit or scope of the invention as defined in the appended claims.

What is claimed is:

l. A regenerative heat exchanger having a rotor, a stationary casing structure including a central portion and an outer portion surround-.

ing said rotor, head plate structures at the ends of said casing structure provided with a plurality of apertures for separated flow of different gas- -eous media therethrough, said head plate structures being rigidly connected to the central portion of said casing structure and being connected to said outer portion of the casingstructure to permit radial movement of the head plate structure relative to said outer portion of the casing structure.

2. A regenerative heat exchanger including a rotor, a stationary casing structure including a central portion and an outer portion surrounding said rotor, head plate structures at each end of said casing structure provided with a plurality of apertures for separated fiow of diiferent gaseous media therethrough, said head plate structures being rigidly connected to the central portion of the casing structure and means including bolts and springs for resiliently connecting said head plate structures to the outer portion of said casing structure, to permit radial expansion of the head plate structure with respect to said outer portion of the casing structure.

3. A.regenerative heat exchanger including a stationary casing structure having a central portion and an outer portion for enclosing a rotor, apertured head plate structures at the ends of said casing structure, said head plate structures being rigidly connected to the central portion of the casing and connected to the outer portion of the casing for radial expansion with respect thereto, and a rotor mounted in said cashaving a circumferentially extending belt of heat insulating material secured to its peripheral wall whereby to locate said air space between the insulation' and the casing. i

4. A regenerative heat exchanger including a stationary casing structure for enclosing a rotor, said casing structure including an outer peripheral portion and a rotor mounted in said casing structure, said rotor having a peripheral 10 wall spaced from the peripheral wall of the casing structure to provide an annular air space cumterentially extending .belt of heat insulating material secured to its peripheral wall whereby to locate said air space between therinsulation and the casing. c

GUSTAV KARL WILLIAM BOESTAD. 

